package org.apache.lucene.index;

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import java.util.Iterator;
import java.util.Map;

import org.apache.lucene.search.Query;
import org.apache.lucene.util.ArrayUtil;
import org.apache.lucene.util.RamUsageEstimator;
import org.apache.lucene.index.BufferedDeletesStream.QueryAndLimit;

/** Holds buffered deletes by term or query, once pushed.
 *  Pushed deletes are write-once, so we shift to more
 *  memory efficient data structure to hold them.  We don't
 *  hold docIDs because these are applied on flush. */

class FrozenBufferedDeletes {

    /* Query we often undercount (say 24 bytes), plus int. */
    final static int BYTES_PER_DEL_QUERY = RamUsageEstimator.NUM_BYTES_OBJECT_REF + RamUsageEstimator.NUM_BYTES_INT + 24;

    // Terms, in sorted order:
    final PrefixCodedTerms terms;
    int termCount; // just for debugging

    // Parallel array of deleted query, and the docIDUpto for
    // each
    final Query[] queries;
    final int[] queryLimits;
    final int bytesUsed;
    final int numTermDeletes;
    final long gen;

    public FrozenBufferedDeletes(BufferedDeletes deletes, long gen) {
        Term termsArray[] = deletes.terms.keySet().toArray(new Term[deletes.terms.size()]);
        termCount = termsArray.length;
        ArrayUtil.mergeSort(termsArray);
        PrefixCodedTerms.Builder builder = new PrefixCodedTerms.Builder();
        for (Term term : termsArray) {
            builder.add(term);
        }
        terms = builder.finish();

        queries = new Query[deletes.queries.size()];
        queryLimits = new int[deletes.queries.size()];
        int upto = 0;
        for (Map.Entry<Query, Integer> ent : deletes.queries.entrySet()) {
            queries[upto] = ent.getKey();
            queryLimits[upto] = ent.getValue();
            upto++;
        }

        bytesUsed = (int) terms.getSizeInBytes() + queries.length * BYTES_PER_DEL_QUERY;
        numTermDeletes = deletes.numTermDeletes.get();
        this.gen = gen;
    }

    public Iterable<Term> termsIterable() {
        return new Iterable<Term>() {
            // @Override -- not until Java 1.6
            public Iterator<Term> iterator() {
                return terms.iterator();
            }
        };
    }

    public Iterable<QueryAndLimit> queriesIterable() {
        return new Iterable<QueryAndLimit>() {
            // @Override -- not until Java 1.6
            public Iterator<QueryAndLimit> iterator() {
                return new Iterator<QueryAndLimit>() {
                    private int upto;

                    // @Override -- not until Java 1.6
                    public boolean hasNext() {
                        return upto < queries.length;
                    }

                    // @Override -- not until Java 1.6
                    public QueryAndLimit next() {
                        QueryAndLimit ret = new QueryAndLimit(queries[upto], queryLimits[upto]);
                        upto++;
                        return ret;
                    }

                    // @Override -- not until Java 1.6
                    public void remove() {
                        throw new UnsupportedOperationException();
                    }
                };
            }
        };
    }

    @Override
    public String toString() {
        String s = "";
        if (numTermDeletes != 0) {
            s += " " + numTermDeletes + " deleted terms (unique count=" + termCount + ")";
        }
        if (queries.length != 0) {
            s += " " + queries.length + " deleted queries";
        }
        if (bytesUsed != 0) {
            s += " bytesUsed=" + bytesUsed;
        }

        return s;
    }

    boolean any() {
        return termCount > 0 || queries.length > 0;
    }
}
